Characterization of Siva in Nervous System Development and Apoptosis

描述（由申请人提供）：中枢神经系统中细胞凋亡程序的激活根据具体情况具有不同的后果。而细胞凋亡是必要的适当胚胎神经系统的发展，细胞死亡发生后，神经元损伤和神经退行性疾病在成年人有不利的后果。p53肿瘤抑制因子是细胞死亡的调节因子，已知其在神经元疾病的神经管正常闭合和细胞凋亡中均起作用。为了更好地理解p53诱导细胞凋亡的机制，我们进行了筛选，在细胞死亡过程中选择性地激活p53的靶基因，我们确定了促凋亡基因Siva。我们已经表明，Siva是既足以诱导细胞死亡和DNA损伤诱导，p53依赖性细胞凋亡培养的神经元。此外，初步结果表明，我们产生的Siva基因敲除小鼠显示胚胎致死性，伴有神经管闭合缺陷。该项目的总体目标是更好地定义1）湿婆在神经系统发育中的作用和2）湿婆在神经细胞死亡中的作用机制。为了了解Siva在神经管闭合和大脑发育中的发育功能，我们将对胚胎发育过程中Siva的表达进行详细分析，并对与Siva缺乏相关的表型进行仔细的形态学和组织学检查。将通过检查细胞凋亡、增殖和分化标志物来研究Siva损失后观察到的缺陷的分子基础。为了阐明Siva在细胞凋亡中的作用机制，我们将描述神经元中Siva表达诱导的细胞凋亡的特征，并定义Siva诱导细胞死亡所必需的细胞凋亡机制的组成部分。鉴于p53依赖性细胞凋亡在神经元疾病中的作用，Siva可能会导致以神经元丢失为特征的人类神经系统疾病，无论是在急性神经元损伤后，如缺血性中风和创伤性脑损伤后，还是在神经元丢失的慢性疾病中，包括阿尔茨海默氏症，帕金森氏症和亨廷顿氏症。因此，我们对Siva的分析将提供对先天性神经系统疾病和成人神经元疾病的深入了解，Siva可能代表治疗以过度神经元细胞死亡为特征的疾病的有希望的治疗靶点。细胞凋亡是细胞自杀的一种形式，其在发育期间塑造胚胎神经系统中起重要作用，但在神经元损伤和成人神经退行性疾病中具有有害后果。我们对基因Siva（一种神经元细胞死亡的强效诱导剂）的分析将为先天性神经系统疾病和成人神经元疾病提供深入了解。此外，由于其在神经元凋亡中的作用，Siva代表了用于治疗以过度神经元细胞死亡为特征的疾病的有希望的治疗靶点。

DESCRIPTION (provided by applicant): Activation of an apoptotic program in the central nervous system has different consequences depending on the specific context. Whereas apoptosis is essential for proper embryonic nervous system development, cell death occurring following neuronal injury and in neurodegenerative disease in adults has detrimental consequences. The p53 tumor suppressor is a regulator of cell death known to play a role both in proper neural tube closure and in apoptosis in neuronal diseases. To better understand the mechanism of p53- induced apoptosis, we performed a screen for target genes activated by p53 selectively during cell death, and we identified the pro-apoptotic gene Siva. We have shown that Siva is both sufficient to induce cell death and necessary for DNA-damage-induced, p53-dependent apoptosis in cultured neurons. Moreover, preliminary results indicate that Siva null mice we generated display embryonic lethality accompanied by neural tube closure defects. The overall goal of this project is to better define both 1) Siva's role in nervous system development and 2) Siva's mechanism of action in neuronal cell death. To understand Siva's developmental function in neural tube closure and brain development, we will perform a detailed analysis of Siva expression during embryogenesis coupled with a careful morphological and histological examination of the phenotypes associated with Siva-deficiency. The molecular basis of the defects observed upon Siva loss will be investigated by examining apoptosis, proliferation and differentiation markers. To elucidate the mechanism of action of Siva in apoptosis, we will characterize those features of apoptosis induced by Siva expression in neurons, and define components of the apoptotic machinery essential for Siva-induced cell death. Given the role of p53-dependent apoptosis in neuronal disease, Siva may contribute to human neurological disorders characterized by neuronal loss, either after acute neuronal injury, such as following ischemic stroke and traumatic brain injury, or in chronic diseases of neuronal loss, including Alzheimer's, Parkinson's, and Huntington's. Thus, our analyses of Siva will provide insight into congenital nervous system disorders and adult neuronal diseases and Siva may represent a promising therapeutic target for treating diseases characterized by excessive neuronal cell death. Apoptosis is a form of cellular suicide that plays an important part in sculpting the embryonic nervous system during development, but has detrimental consequences following neuronal injury and in neurodegenerative disease in adults. Our analyses of the gene Siva, a potent inducer of cell death in neurons, will provide insight into both congenital nervous system disorders and adult neuronal diseases. Moreover, because of its role in neuronal apoptosis, Siva represents a promising therapeutic target for treating diseases characterized by excessive neuronal cell death.